In wireless telecommunication networks, such as cellular wireless networks, a radio access network (RAN) may communicate with a mobile station by transmitting forward link signals and the mobile station may communicate with the RAN by transmitting reverse link signals. When the mobile station is engaged in a call, the RAN may use a forward traffic channel to transmit forward link signals to the mobile station over and the mobile station may use a reverse traffic channel to transmit reverse link signals to the RAN.
During the call, the mobile station may monitor the forward link signals that the RAN transmits over the forward traffic channel. If the mobile station determines that it has lost contact with the RAN, the mobile station may disable its transmitter, thereby discontinuing its use of the reverse traffic channel. In a conventional approach, the mobile station determines that it has lost contact with the RAN when the mobile station fails to receive usable forward traffic channel frames during a fixed period of time.
For example, a recent spread spectrum standard, 3rd Generation Partnership Project, “Upper Layer (Layer 3) Signaling Standard for cdma2000 Spread Spectrum Systems,” Revision E, 3GPP2 C.S0005-E, September 2009 (hereinafter “3GPP2 Standard”) defines a constant, N2m. The N2m, constant is described as follows: “The duration, of insufficient signal quality (e.g. bad frames), in units of 20 ms, received on the Forward Traffic Channel before a mobile station must disable its transmitter.” See 3GPP2 Standard, Table D-2 on page D-8. The N2m constant is given a value of 12 frames (i.e., 240 ms) in this standard. Id.